GENEVA: Delegations from some 140 countries have agreed to adopt a ground-breaking treaty limiting the use of health-hazardous mercury, the Swiss foreign ministry said Saturday.

The world's first legally binding treaty on mercury, reached after a week of thorny talks, will aim to reduce global emission levels of the toxic heavy metal also known as quicksilver, which poses risks to human health and the environment.

Switzerland, which along with Norway initiated the process a decade ago, hailed the consensus on the issue.

“The new treaty aims to reduce the production and the use of mercury, especially in the production of products and in industrial processes,” the Swiss foreign ministry said in a statement.

Countries will be asked to sign the treaty next October in Minamata, Japan, in honour of the town's inhabitants who for decades have suffered the consequences of serious mercury contamination, the statement said.

“The adoption of the mercury treaty shows the vitality of international environmental politics and the will of states to together find solutions to world problems,” head of the Swiss delegation to the talks, Franz Perrez, said in the statement.

Mercury is found in products ranging from electrical switches to thermometers to light-bulbs, to amalgam dental fillings and even facial creams, and large amounts of the heavy metal are released from small-scale gold mining, coal-burning power plants, metal smelters and cement production.

Serious mercury poisoning affects the body's immune system and can lead to problems including psychological disorders, loss of teeth and problems with the digestive, cardiovascular and respiratory tracts.

It also affects development of the brain and nervous system and poses the greatest risk to foetuses and infants.

Ahead of the Geneva conference, the UN's environmental programme provided the first global assessment of releases of mercury into rivers and lakes.

“In the past 100 years, man-made emissions have caused the amount of mercury in the top 100 metres of the world's oceans to double. Concentrations in deeper waters have increased by up to 25 per cent,” the agency said, adding that much human exposure to mercury is through the consumption of contaminated fish.

UNEP also highlighted rising levels of mercury in the Arctic, where 200 tonnes of the substance are deposited every year.

The UN agency's study also found that developing countries were especially vulnerable to direct mercury contamination owing mainly to the widespread use of the element in small-scale gold mining and to the burning of coal for electricity generation.

Such exposure “poses a direct threat to the health of some 10-15 million people who are directly involved in small scale gold mining, mainly in Africa, Asia and South America,” UNEP said.